1. Field of Invention
The present invention relates to a system and a method for regenerating a particulate filter. More particularly, the present invention relates to a system and method for regenerating a particulate filter of a gasoline engine.
2. Description of Related Art
Generally, a gasoline direct injection (GDI) art has been developed so as to improve fuel consumption efficiency and performance of an internal combustion engine, wherein the GDI engine does not inject fuel into an intake pipe, but directly injects the fuel into a combustion chamber.
Since the air/fuel ratio is low (rich mode) around a spark plug, an engine is operated in a lean fuel condition, but there is a problem that a gasoline direct injection engine (GDI) generates a large amount of particulate matter (PM) according to an incomplete combustion period increment in a combustion chamber.
Accordingly, a particulate filter is mounted in a gasoline direct injection engine (GDI) vehicle. Because the temperature in the particulate filter, however, is low and oxygen concentration in the particulate filter is low, it is difficult to passively regenerate particulate matter (PM) in the particulate filter.
In a conventional art, various devices for supplying oxygen to a particulate filter have been developed so as to resolve such problems. That is, regeneration of the particulate filter is performed as a consequence of the particulate matter (PM) trapped in the particulate filter being oxidized and eliminated by supplying additional air to the front end of the particulate filter mounted on an exhaust pipe.
Exhaust gas exhausted from the gasoline engine is purified when passing through a three-way catalyst device. Particularly, when the air-fuel ratio in a cylinder is a stoichiometric air-fuel ratio, the exhaust gas can be very effectively purified. If air, however, is additionally supplied for regenerating the particulate filter (i.e., the air/fuel ratio is high), nitrogen oxide (NOX) in the exhaust gas is hardly reduced.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.